I don't usually post spoiler warnings but since this will be about a book whose primary purpose is plot twists and a similar movie then I thought this might be a nice touch.
Lee Child started the Jack Reacher series with his first novel, 1997's Killing Floor. It's a reasonably effective crime thriller laced with the grotesque violence that so many writers feel is necessary to show how hardboiled they are. The premise of Reacher as a former military cop who's now a drifter obviously draws from Westerns and solves a lot of problems in writing a series since there's no need to explain how he got anywhere, tie up any loose ends or even explain why he knows anything.
Killing Floor has Reacher in a small Georgia town chosen for an arbitrary reason but he soon gets involved in a murder investigation. It has the usual small town scheming, hired thugs, local bad boys, surprise events and sexual encounters that are driven purely by genre needs. As you might expect Reacher is something of a super-detective, always one step ahead of the cops and rarely wrong. The most interesting part might be when he's in prison and I halfway expected (or at least hoped) him to be there for the entire novel. He's of course not concerned about The Law but about Justice and in at least one situation basically murders a couple of men - they do turn about to be guys planning to kill him but when he did that he only had a suspicion nothing concrete.
The oddest thing about the book is some outrageous coincidences. The biggest is that Reacher gets off at that particular town because it was the home to a blues musician that his brother told him about years ago. And then the murder victim turns out to be Reacher's brother but he was in town for reasons completely unconnected to Reacher's. That two brothers would be in the same small town at the same time unknown to each other and for completely different reasons (and then one is arrested for the murder of the other) is so outlandish that Child even has Reacher muse on it before deciding that life is full of coincidences. True but art shouldn't be unless there's a particular point (or it's a structuring principle as with Lost). In this case it's clear that first-time novelist Child created a situation that he couldn't (or didn't want to spend the time) resolve. It's this inexperience that's also why the novel has so little flavor. It's set in rural Georgia but could just as well have been anywhere in the country. There's not much in the way of anything unique to that region and sure Child is British but if he didn't want to do the research then he could have just made it up. On the other hand that's what he apparently did with a description of the Atlanta airport that's completely wrong.
The film Jack Reacher (Christopher McQuarrie 2012) is based on a later novel in the series and is in most ways more effective though it too ends with implausible plot devices. (It's not well served by a trailer that makes this look like more of an ubermensch action film.) Tom Cruise was a good choice to play Reacher since as an actor he's mostly a blank and Reacher borders on the anonymous. Rosamund Pike, though, seems to have not been told she's in a genre film since at times she's performing as if for something altogether more naturalist. The film is taut and if not really unpredictable then at least twisty enough. The dialogue is definitely sharper than usual and at least some of Reacher's investigation follows a logical path (though he still is rarely wrong).
It's main flaw is some of the plotting and motivation which apparently come from the novel (which I haven't read). At one point Reacher tracks down somebody because she said "THE auto parts store" instead of "AN auto parts store" so he has the lawyer take him to the city's THE store. This is ridiculously slender to be charitable - actually it's basically impossible and was papering over a plot point. (I call the place where I work THE store even though it's not remotely THE store for my city.)
But when we get to the reason why all of this is happening everything becomes more and more outlandish. Apparently a criminal-backed real estate company pressures people to sell for cheap, develops property then sells at a profit. The pressure seems to consist of assorted nefarious activity and in this case they orchestrated a mass murder to hide a single murder. Sure we wouldn't have this story if they had done otherwise but when any kind of garden-variety killing would have worked it's hard not to tug at that thread. I'm sure the filmmakers realize this since they zip through this part very quickly. They also zip over why a civilian would come help Reacher in what is also clearly illegal. (I also always wonder how lunatic criminal "masterminds" who kill their underlings ever manage to get more - though in this case the "mastermind" is so lethargic that I half expected another reveal towards the end of somebody else behind the whole affair.)